然后是一段relabel_configs配置，其作用主要是用于匹配最终要抓取的endpoint，构造抓取的地址，甚至给最终的时序指标加上一些label。这里以apiserver发现的node_exporter endpoint信息为例，在没有relabel之前，其endpoint信息如下： ``` __address__="192.168.65.3:9100" __meta_kubernetes_endpoint_address_target_kind="Pod" __meta_kubernetes_endpoint_address_target_name="prometheus-node-exporter-89tcq" __meta_kubernetes_endpoint_port_name="metrics" __meta_kubernetes_endpoint_port_protocol="TCP" __meta_kubernetes_endpoint_ready="true" __meta_kubernetes_endpoints_name="prometheus-node-exporter" __meta_kubernetes_namespace="default" __meta_kubernetes_pod_container_name="prometheus-node-exporter" __meta_kubernetes_pod_container_port_name="metrics" __meta_kubernetes_pod_container_port_number="9100" __meta_kubernetes_pod_container_port_protocol="TCP" __meta_kubernetes_pod_controller_kind="DaemonSet" __meta_kubernetes_pod_controller_name="prometheus-node-exporter" __meta_kubernetes_pod_host_ip="192.168.65.3" __meta_kubernetes_pod_ip="192.168.65.3" __meta_kubernetes_pod_label_app="prometheus" __meta_kubernetes_pod_label_component="node-exporter" __meta_kubernetes_pod_label_controller_revision_hash="1203132889" __meta_kubernetes_pod_label_pod_template_generation="1" __meta_kubernetes_pod_label_release="prometheus" __meta_kubernetes_pod_name="prometheus-node-exporter-89tcq" __meta_kubernetes_pod_node_name="docker-for-desktop" __meta_kubernetes_pod_ready="true" __meta_kubernetes_pod_uid="62b53ba7-eae3-11e8-b0a6-025000000001" __meta_kubernetes_service_annotation_prometheus_io_scrape="true" __meta_kubernetes_service_label_app="prometheus" __meta_kubernetes_service_label_chart="prometheus-7.4.1" __meta_kubernetes_service_label_component="node-exporter" __meta_kubernetes_service_label_heritage="Tiller" __meta_kubernetes_service_label_release="prometheus" __meta_kubernetes_service_name="prometheus-node-exporter" __metrics_path__="/metrics" __scheme__="http" job="kubernetes-service-endpoints" ``` ### 通过kubernetes_sd_configs发现机制，通过apiserver的接口列出当前k8s集群中endpoints列表 经过下面的relabel规则后： ``` - job_name: kubernetes-service-endpoints kubernetes_sd_configs: - role: endpoints relabel_configs: - action: keep regex: true source_labels: - __meta_kubernetes_service_annotation_prometheus_io_scrape # 只匹配__meta_kubernetes_service_annotation_prometheus_io_scrape=true的endpoint # 然后进行下一步 # 如果有__meta_kubernetes_service_annotation_prometheus_io_scheme，且正则匹配(https?)，则将__scheme__修改为__meta_kubernetes_service_annotation_prometheus_io_scheme指定的值 - action: replace regex: (https?) source_labels: - __meta_kubernetes_service_annotation_prometheus_io_scheme target_label: __scheme__ # 如果有__meta_kubernetes_service_annotation_prometheus_io_path，且正则匹配(.+)，则将__metrics_path__修改为__meta_kubernetes_service_annotation_prometheus_io_path指定的值 - action: replace regex: (.+) source_labels: - __meta_kubernetes_service_annotation_prometheus_io_path target_label: __metrics_path__ # 如果有__address__;__meta_kubernetes_service_annotation_prometheus_io_port，且正则匹配([^:]+)(?::\d+)?;(\d+)，则将__address__修改为$1:$2指定的值 - action: replace regex: ([^:]+)(?::\d+)?;(\d+) replacement: $1:$2 source_labels: - __address__ - __meta_kubernetes_service_annotation_prometheus_io_port target_label: __address__ # 如果label名称正则匹配__meta_kubernetes_service_label_(.+)，则设置相应的label - action: labelmap regex: __meta_kubernetes_service_label_(.+) # 设置kubernetes_namespace为__meta_kubernetes_namespace的值 - action: replace source_labels: - __meta_kubernetes_namespace target_label: kubernetes_namespace # 设置kubernetes_name为__meta_kubernetes_service_name的值 - action: replace source_labels: - __meta_kubernetes_service_name target_label: kubernetes_name ``` 最终形成的抓取endpoint信息如下： ``` __address__="192.168.65.3:9100" app="prometheus" chart="prometheus-7.4.1" component="node-exporter" heritage="Tiller" release="prometheus" kubernetes_namespace="default" kubernetes_service_name="prometheus-node-exporter" __metrics_path__="/metrics" __scheme__="http" job="kubernetes-service-endpoints" ``` 上述的endpoint信息交由prometheus，prometheus就可以得到抓取地址了，为`__scheme__://__address____metrics_path__`，也即`http://192.168.65.3:9100/metrics`